Perhaps they want to explore different character dynamics. By creating a situation where the guild 'hates' Lucy, they can develop new storylines and interactions that wouldn't be possible in the original plot. It gives them creative freedom to play with the characters' emotions and relationships in a new way.
It could also be a way for the writer to express their own feelings of dissatisfaction with Lucy's character in a more extreme way. They might not like certain aspects of her personality or her role in the series, and writing this type of fanfiction allows them to rewrite the story according to their own views, even if it means creating a negative scenario for her.
Sure, there may exist such fanfictions. In the official 'Fairy Tail' story, Natsu and Lucy are very close. But fanfiction is a world of creativity and deviation from the original. A writer might decide to make Natsu hate Lucy due to some made - up reasons like a misunderstanding or a conflict of interests. This could lead to a whole new set of adventures or conflicts within the 'Fairy Tail' universe as rewritten by the fanfiction author.
Some people like it because it offers a new and different relationship dynamic compared to the more common pairings in 'Fairy Tail'. Midnight has an interesting character with his own powers and backstory, and pairing him with Lucy creates unique story possibilities.
Some people might write it for creative freedom. They see the 'Fairy Tail' world as a starting point, but they want to explore different ideas and concepts that go against the original narrative. They might have different views on the power levels of characters, for example, and use the fanfiction to change that. Another aspect could be that they want to start discussions among other fans. By presenting an alternative view in the form of 'fairy tail bashing fanfiction', they hope to engage with others who may have similar or opposing views.
One common theme could be jealousy among the other characters towards Lucy. Maybe they envy her magic or her relationships within the guild.
Well, in fanfiction, Lucy might be crying because she lost a fight against a powerful enemy. Maybe she felt she let her friends down. For example, if she was unable to protect someone important in the story, it could lead to her breaking down in tears.
It could be that the characters in Naruto have a distinct personality and world - view that don't mesh well with the Fairy Tail universe in fanfiction. For example, Naruto's values of hard work and friendship in his own ninja world are different from how they might be portrayed when forced into the Fairy Tail setting. Fans who are loyal to Naruto's original concept might hate seeing it distorted in Fairy Tail fanfiction.
Maybe Natsu hates Fairy Tail fanfiction because he doesn't like how some fanfictions distort the original story or the characters. In the original Fairy Tail, he has a clear personality and relationships, and fanfictions might change that in ways he wouldn't like.
People write 'naruto weak fairy tail fanfic' to explore new and different storylines. It's interesting to see how a character like Naruto, who is strong in his own universe, would cope in the Fairy Tail world where the rules are so different. It allows for a lot of creativity.
People like to watch Fairy Tail fanfiction because it allows them to explore different storylines and scenarios that the original series might not have covered. It gives fans a chance to see their favorite characters in new situations, like different romantic pairings or epic battles in alternate universes.
People like to write Laxus and Lucy fanfiction because they are both interesting characters. Laxus is strong and has a complex personality, while Lucy is kind - hearted and has her unique magic. Combining them in a story can create a lot of interesting interactions and storylines.